1. Field of the Invention
This invention relates to a member used in a thin film forming apparatus, a plasma treating apparatus or the like in a semiconductor processing process and a method of producing the same, and more particularly to a spray-coated member having an excellent resistance to plasma erosion, which is used as a member for a container used in the plasma processing under an environment containing a halogen compound, for example, a containing used in vacuum deposition, ion plating, sputtering, chemical deposition, laser precision working, plasma sputtering or the like, and a method of producing the same.
2. Description of Related Art
In the semiconductor processing process, there is a step of forming a thin film of a metal, a metal oxide, a nitride, a carbide, a boride, a silicide or the like. In this step is used a thin film-forming apparatus for vacuum deposition, ion plating, sputtering, plasma CVD or the like (e.g. JP-A-50-75370).
When the thin film is formed with such an apparatus, a thin film forming material adheres onto surfaces of various jigs or constituents used in the apparatus. When the adhesion amount of the thin film forming material onto the jig or the constituent is small, the troubles are hardly caused. However, the time of forming the thin film becomes recently long, and hence the adhesion amount of particles to the jig or the constituent increases, and also the change of temperature in the operation and the variation of mechanical load to the jig or the constituent become large. As a result, there is caused a problem that a part of the particles as a main component of the thin film adhered to the surface of the jig or constituent during the formation of the thin film is adhered to a semiconductor wafer through the peeling and scattering to deteriorate the quality of the product.
As to the various constituents used in the aforementioned apparatuses, the following methods are proposed as a technique of preventing the peeling of the thin film-forming particles adhered to the surface of the constituent. For example, JP-A-58-202535 and JP-B-7-35568 disclose a technique that the surface of the jig or the constituent is subjected to a sand blasting and further to a horning or knitting to roughen the surface to thereby increase the surface area effective for preventing the peeling and scattering of the adhered thin-film particles.
JP-A-H03-247769 discloses a technique that U-shaped grooves or V-shaped grooves are periodically formed on the surface of the jig or the constituent at intervals of not more than 5 mm to suppress the peeling of the thin film forming particles.
JP-A-H04-202660 and JP-A-H07-102366 disclose a technique that TiN coating is formed on the surface of the constituent or further a fusion plated coating of Al or Al alloy is formed thereon. Also, JP-A-H06-220618 discloses a technique that Ti—Cu material is spray coated and only Cu is removed with HNO3 to form a coating of a porous surface structure having a large specific surface area to thereby suppress the scattering of the adhered thin film-forming particles.
In Japanese Patent No. 3076768 is proposed a technique that a metal is sprayed onto a surface of a metal member at a metal net adhered state or a metal is sprayed and a metal net is adhered thereon and a metal is again sprayed, and thereafter the metal net is pulled out to form lattice-shaped unevenness on the spray coating, whereby the specific surface area is increased to allow the great amount of the thin film-forming particles adhered thereto.
However, the precision in the recent processing of the semiconductor becomes higher and hence the cleanness of the processing environment becomes further severer. Particularly, when the processing of the semiconductor is carried out by plasma sputtering treatment in a halogen gas or a halogen compound gas, it is required to take a countermeasure on corrosive product produced on the surface of the jig or constituent, which is arranged in the apparatus for this treatment or finer particles generated from the surface of the constituent through sputtering phenomenon.
That is, the rescattering of the thin film forming particles in the formation of the thin film comes into problem in the semiconductor processing process. Also, in the plasma etching process, not only the processing of the semiconductor but also the surrounding members are affected by the etching to generate fine particles, which is pointed out to exert on the quality of the semiconductor product. As a countermeasure therefor, JP-A-2004-52281 recommends that a quartz is used as a substrate so as to have a surface roughness of 3-18 μm and a spray coating of Al2O3 or TiO2 is directly formed thereon and the surface of the spray coating is made to a roughened surface indicating a negative value of less than 0.1 as a skewness (Rsk) of a roughness curve.
Further, JP-A-2000-191370, JP-A-H11-345780, JP-A-2000-72529 and JP-B-H10-330971 disclose a technique for increasing the adhesion and deposited volume of the particles, while JP-A-2000-228398 discloses a technique of forming convex and concave portions dividing the adhered film to reduce the scattering.
in the semiconductor processing process, the conventional techniques have the following problems:
(1) Problems in the Thin Film Forming Process
(a) The techniques disclosed in the above patent articles for preventing the phenomenon of adhering the thin film forming particles to the jig and constituent in the thin film forming process and the scattering thereof, i.e. the method of enlarging the adhesion area of the thin film forming particle by various means recognize a constant effect on the long-time operation for the thin film formation and the improvement of the production efficiency accompanied therewith, but the adhered and deposited thin film forming particles are finally rescattered, so that they can not be a fundamental solution.(b) Since a surface-treated film formed or treated on the surface of the jig or constituent adhered and deposited with a great amount of the thin film forming particles is a metallic coating, when the thin film forming particles are removed with an acid or an alkali, the surface treated film is simultaneously dissolved, and hence the usable number through the reproduction becomes small, which is a cause of increasing the coat of the product.(c) The means for enlarging the adhesion area of the thin film forming particles in the conventional techniques merely intends only the enlargement of the area, but does not propose the method of preventing the scattering of the adhered thin film forming particles.(2) Problems in the Plasma Etching Process
As disclosed in JP-A-2004-52281, the countermeasure for the jig and constituent used in the plasma etching process proposes a technique that the spray coating of Al2O3 or TiO2 is formed on the surface of quartz substrate and also the surface roughness of the spray coating is controlled to a negative value of less than 0.1 of Rsk (skewness of roughness curve), whereby fine particles generated by sputtering phenomenon is received with the surface of the coating having such a roughness curve. However, TiO2 disclosed in this technique is corroded or etched under an environment of the plasma etching containing a halogen gas to produce a great amount of particles as a contamination source. On the other hand, the spray coating of Al2O3 is superior to TiO2 coating in the corrosion resistance and resistance to plasma etching, but is short in the service life, and also the surface form indicating the negative value of Rsk: less than 0.1 is less in the adhesion and deposition amount of the environment contaminating substance and is saturated in a short time, so that the remaining forms a source for generating particles. Further, there is a problem that the convex portions of the surface form show a geometric form being large in the area and easily depositing a great amount of particles thereon and easily rescattering them.
As disclosed in JP-A-H10-4083, a technique of using a single crystal of Y2O3 as a material having a resistance to plasma erosion limits the application because it is difficult to form the coating of such a material. Also, a technique disclosed JP-A-2001-164354 proposing a spray coating of Y2O3 is excellent in the resistance to plasma erosion, but does not examine the adhesion and deposition of the environment contaminating particles.